MIC2145
Micrel, Inc.
MIC2145
High Efficiency 2.5W Boost Converter
General Description
The MIC2145 is a small size boost switching regulator that
can provide over 2.5W of output power. The input voltage
range is between 2.4V to 16V, making the device suitable for
one-cell Li-Ion and 3- to 4-cell alkaline/NiCad/NiMH applica-
tions. The output voltage of the MIC2145 can be adjusted up
to 16V.
The MIC2145 is well suited for portable, space-sensitive
applications. Its typical 450kHz operation allows small sur-
face mount external components to be used. The MIC2145
has a low quiescent current of 200µA, and a typical shutdown
current of 0.5µA. The MIC2145 is capable of high efficiencies
in a small board area.
The MIC2145 features a low-on resistance internal switch
that allows it to provide over 2.5W of output power. The peak
switch current can be programmed through an external
resistor. This allows the user to set the peak switch current at
the level where maximum efficiency occurs. It also allows the
user to further optimize for efficiency and inductor size by
setting the peak current below the level of inductor saturation.
The MIC2145 is available in an MSOP-8 and 3mm×3mm
MLF™-10L package with an ambient operating temperature
range from –40°C to +85°C.
Features
2.4V to 16V input voltage
Output adjustable to 16V
Programmable peak current limit
Soft start
Up to 450kHz switching frequency
0.5µA shutdown current
200µA quiescent current
Capable of 5V/ 500mA output with 3.3V input
Achieves over 85% efficiency
Implements low power BOOST, SEPIC, and FLYBACK
topologies
• MSOP-8 and 3mm×3mm MLF™-10L
•
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Applications
•
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Flash LED driver
LCD bias supply
White LED driver
DSL bias supply
Local 3V to 5V conversion
Ordering Information
Part Number
Standard
Pb-Free
MIC2145BMM
MIC2145BML
MIC2145YMM
MIC2145YML
Voltage
Adj
Adj
Ambient
Temp. Range
–40°C to +85°C
–40°C to +85°C
Package
8-lead MSOP
10-lead MLF™
Typical Application
V
IN
3.0V to 5.0V
C
IN
10µF/6.3V
1
L1
10µH
D1
EN
PGND
SW
VDD
FB
SGND
5
10V Output
Efficiency
90
V
OUT
10V/150mA
EFFICIENCY (%)
85
80
75
70
65
60
10
V
IN
= 3.0V
100
1000
OUTPUT CURRENT (mA)
4
6
MIC2145BMM
3
C
OUT
10µF/16V
7
RSET
SS
2
8
I Limit
Adjustable Output Boost Converter with Programmable Peak Switch Current
MLF and
MicroLeadFrame
are trademarks of Amkor Technologies, Inc.
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
April 2005
1
M9999-042205
MIC2145
Micrel, Inc.
Pin Configuration
EN 1
SS 2
RSET 3
PGND 4
8 SGND
7 FB
6 VDD
5 SW
EN
1
SS
2
RSET
3
PGND
4
PGND
5
10
SGND
9
FB
8
VDD
7
SW
6
SW
8-Lead MSOP (MM)
×
3mm×3mm MLF-10L (ML)
Pin Description
Pin Number
MSOP
1
2
3
4
5
6
7
8
Pin Number
MLF
1
2
3
4, 5
6, 7
8
9
10
Pin Name
EN
SS
RSET
PGND
SW
VDD
FB
SGND
Pin Function
Enable (Input): Logic high (≥1.5V) enables regulator. Logic low (≤0.7V)
shuts down regulator. Do not float.
Soft Start Capacitor (External Component): Connect external capacitor to
ground to control the rise time of the output voltage.
Current Limit (External Component): Sets peak current limit of the internal
power MOSFET using an external resistor.
Power Ground (Return): Internal power MOSFET source.
Switch Node (Input): Internal power MOSFET drain.
Supply (Input): +2.4V to +16V for internal circuitry.
Feedback (Input): Output voltage sense node.
Small Signal Ground (Return): Ground
M9999-042205
2
April 2005
MIC2145
Micrel, Inc.
Absolute Maximum Ratings
(Note 1)
Supply Voltage (V
DD
) .................................................... 18V
Switch Voltage (V
SW
) .................................................... 18V
Feedback Voltage (V
FB
) ................................................ 18V
Switch Current (I
SW
) ........................................................ 2A
Enable Voltage(V
EN
),
Note 5 ........................................
18V
RSET Voltage (V
RSET
) .................................................... 6V
ESD Rating,
Note 3 ......................................................
2kV
Ambient Storage Temperature(T
S
) .......... –65°C to +150°C
Operating Ratings
(Note 2)
Supply Voltage (V
DD
) ....................................... 2.4V to 16V
Switch Voltage (V
SW
) .................................................... 16V
Ambient Temperature (T
A
) ......................... –40°C to +85°C
Junction Temperature (T
J
) ....................... –40°C to +125°C
Package Thermal Resistance MSOP
θ
JA
(MSOP-8) .................................................... 206°C/W
θ
JA
(3mm×3mm MLF-10) .................................... 60°C/W
Electrical Characteristics
(Note 6)
V
DD
= 10V, V
OUT
= 10V, I
OUT
= 100mA; T
J
=25°C, unless otherwise noted,
bold
values indicate –40°C
≤
T
J
≤
125°C.
Parameter
Supply Voltage
Shutdown Current
Quiescent Current
Feedback Voltage Reference
EN = 0.3V, V
DD
= 10V, V
FB
=1.35V
EN = V
DD
, V
DD
= 10V, V
FB
= 1.35V
(±2%)
(±3%)
Comparator Hysteresis
Feedback Input Current
Peak Current Limit
V
FB
=1.35V
R
SET
=200Ω, V
DD
= 3.6V,
Note 4
R
SET
=1kΩ, V
DD
= 10V,
Note 4
Current Limit Comparator
Propagation Delay
Switch On-Resistance
I
SW
= 150mA, V
DD
= 3.0V
I
SW
= 1.2A, V
DD
= 10V
Maximum Off Time
Enable Input Voltage
Logic Low (turn-off)
Logic High (turn-on)
Enable Input Current
V
EN
= 0V
V
EN
= 2V
Soft Start Current
Note 1.
Note 2.
Note 3.
Note 4.
Note 5.
Note 6.
Condition
Min
2.4
Typ
Max
16
Units
V
µA
µA
V
V
mV
nA
A
A
ns
0.5
200
1.058
1.048
18
40
0.8
0.9
500
500
250
1000
1.1
1.5
–1
–1
–8
1.1
0.01
0.01
–12
1.08
5
300
1.102
1.112
750
400
mΩ
mΩ
ns
0.7
V
V
1
1
–16
µA
µA
µA
V
EN
= 2V, V
DD
=3.0V
Exceeding the absolute maximum rating may damage the device.
The device is not guaranteed to function outside its operating rating.
Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5KΩ in series with 100pF.
The current is measured in a DC mode. Actual peak switching current will be higher due to internal propagation delay of the circuit.
V
EN
≤
V
DD
.
Specification for packaged product only.
April 2005
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M9999-042205
MIC2145
Micrel, Inc.
Typical Characteristics
Efficiency-Basic
Configuration
100
90
EFFICIENCY (%)
EFFICIENCY (%)
Efficiency-Bootstrapped
Configuration
100
90
80
70
60
50
V
IN =
3.3V
V
OUT =
10V
L
=
10µH
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
V
OUT
(V)
Load Regulation
10.2
10.0
9.8
9.6
9.4
9.2
V
IN
= 3.6V
L = 10µH
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0
80
70
60
50
V
IN
= 3.3V
V
OUT
= 10V
L = 10µH
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0
OUTPUT CURRENT (A)
0
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
Line Regulation
SWITCH ON-RESISTANCE (Ω)
SWITCH ON-RESISTANCE (Ω)
16.0
15.8
15.6
15.4
V
OUT
(V)
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0
Switch On-Resistance
vs. V
DD
Switch On-Resistance
vs. Temperature
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
15.2
15.0
14.8
14.6
14.4
14.2
14.0
2
4
6
I
OUT
= 10mA
L = 10µH
8 10 12
V
DD
(V)
14
16
2
4
6
8 10 12 14 16 18
V
DD
(V)
QUIESCENT CURRENT (Ω)
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0
2
4
6
8 10 12 14 16 18
V
DD
(V)
1.09
1.08
1.07
1.06
1.05
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
FEEDBACK CURRENT (µA)
FEEDBACK VOLTAGE (V)
0.50
0.45
Quiescent Current
vs. V
DD
Feedback Voltage
vs. Temperature
1.1
0.10
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
Feedback Current
vs. Temperature
0.00
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Off Time
vs. Temperature
1.5
1.4
1.3
SHUTDOWN CURRENT (µA)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
Shutdown Current
vs. Temperature
QUIESCENT CURRENT (mA)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
Quiescent Current
vs. Temperature
OFF TIME (µs)
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
V
IN
= 3.6V
0.00
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
0.00
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
M9999-042205
4
April 2005
MIC2145
Micrel, Inc.
Soft Start Current
vs. Temperature
14
SOFT START CURRENT (µA)
PEAK CURRENT LIMIT (A)
Peak Current Limit
vs. Temperature
1.4
R
SET
= 200
1.3
1.2
1.1 R
= 500
1.0
SET
R
SET
= 1k
0.9
0.8
0.7
0.6
0.5
0.4 V = 3.6V
R
SET
= 10k
0.3
IN
0.2 V
OUT
= 10V
0.1 L = 10µH
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
2000
PEAK CURRENT LIMIT (mA)
Peak Current Limit
vs. RSET
1800
1600
1400
1200
1000
800
600
L = 10µH
5.0V
4.2V
3.6V
3.3V
3.0V
2.4V
VIN =
15V
12V
10V
8.0V
12
10
8
6
4
2
V
IN
= 3.6V
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
400
VOUT/VIN > 1.25
100
1000
10000
RSET(Ω)
100000
April 2005
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M9999-042205
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